Technique for surface mounting electrical components to a circuit board

ABSTRACT

A technique for mounting an electrical component to a circuit board includes deforming each of a number of electrical terminals extending from the electrical component to form a mounting portion and a tip portion extending away from the mounting portion. The circuit board defines a number of bores extending therein from a first surface to a second opposite surface, and the electrical component is mounted to the circuit board with the mounting portion of each of the number of electrical terminals supporting the component against the first surface of the circuit board with each of the tip portions extending into separate ones of the number of bores. The mounting portion of each of the electrical terminals is mechanically and electrically affixed to corresponding electrically conductive pads to thereby surface mount the electrical component to the circuit board. The disclosed technique is particularly advantageous for surface mounting display units.

TECHNICAL FIELD

[0001] The present invention relates generally to techniques formounting electrical components to circuit boards, and more specificallyto techniques for surface mounting electrical components to circuitboards.

BACKGROUND OF THE INVENTION

[0002] Techniques for mounting electrical components to circuit boardsare known and commonly used in the electronics industry. Many suchelectrical components include electrical leads (sometimes referred to as“pins” or “terminals”) extending therefrom, wherein these electricalleads must be mechanically and electrically attached to the circuitboard in forming a desired electrical or electronic circuit.

[0003] Early electrical circuit boards included a number of holes orpassageways defined therethrough, and an electrically conductive filmpatterned on a backside thereof. With such circuit boards, electricalcomponents are typically arranged on a top side of the circuit board,and their electrical leads are passed through appropriate holes definedthrough the board and soldered to the electrically conductive filmpatterned around the various circuit board holes. In this manner,electrical components are arranged on a top side of the circuit board,and mechanically and electrically attached to an opposite back side ofthe circuit board to form a desired electrical or electronic circuit.

[0004] Advances in circuit board technology have provided for so-called“plated-through” hole technology wherein electrically conductive filmcan be patterned on both the top side, the back side and/or within acircuit board, as well as on the sidewalls of the various holes definedthrough the circuit board. Circuit boards implementing plated-throughtechnology provide for the ability to carry out the soldering process oneither or both sides of the circuit board.

[0005] An example of a known electrical circuit assembly techniqueutilizing a plated-through hole circuit board is shown in FIGS. 1A and2. Referring to FIG. 1A, an electrical component 12 is attached to acircuit board 14 via a number of electrical terminals 16 a-16 xextending from component 12. Circuit board 14 includes a correspondingnumber of electrically conductive pads 18 a-18 x defining plated-throughholes 14′ therethrough (see FIG. 2). Referring to FIG. 1B, each of theelectrical terminals 16X conventionally define a region 16X′ extendingfrom component 12 and having a first width or cross-sectional area thatis larger than the cross-sectional area of the circuit board holes 14′,and a region 16X″ extending from region 16 x′ and having a secondreduced width or cross sectional area that is smaller than thecross-sectional area of the circuit board holes 14′. The interfacebetween regions 16X′ and 16X″ typically defines a step that supports thecomponent 12 against the top of the circuit board 14 when the variouselectrical terminals 16 a-16 x are extended through the circuit boardholes 14′. The electrical terminals 16 a-16 x are then electrically andmechanically attached to the corresponding electrically conductive pads18 a-18 x via solder connections 20 a-20 x as illustrated in FIG. 1A.

[0006] Referring to FIG. 2, a cross-section of the circuit assemblyillustrated in FIG. 1A is shown along section lines 2-2. FIG. 2illustrates a known technique for electrically and mechanicallyattaching example electrical leads 16 b and 16 z (not shown in FIG. 1)of electrical component 12 to circuit board 14. For example, electricalterminal 16 b includes a first section 16 b′ extending from electricalcomponent 12 in a direction generally parallel with a top planar surface12 a thereof. A second section 16 b″ of electrical terminal 16 b extendsdownwardly and in a direction substantially normal to the planar face 12a of electrical component 12 and through a hole or passageway 14′defined through circuit board 14. The hole or passageway 14′ isplated-through as shown by electrically conductive film portions 18 b. Asolder connection 20 b forms an electrical and mechanical attachment ofterminal portion 16 b″ to the electrically conductive film portions 18b.

[0007] While the known electrical component mounting techniquesdescribed hereinabove and shown with respect to FIGS. 1A, 1B and 2 havebeen extensively used in the electronics industry, they have certaindrawbacks associated therewith. For example, while some electricalcomponents may be mounted flush and in contact with the top of circuitboard 14, others must be elevated from the top of the circuit board asshown in FIGS. 1 and 2 for various reasons. In such cases, a number ofdrawbacks may result. For example, electrical component 12 may be adisplay unit or other device having a top surface 12 a that must notonly be elevated from circuit board 14, but must also be substantiallyparallel with circuit board 14 for proper viewing thereof. If theelectrical terminals 16 a-16 z are not precisely configured such thateach of the interfaces between terminal portions 16X′ and 16X″ definesubstantially parallel surfaces, special care must then be taken toensure that electrical component 12 is mounted to circuit board 14 insuch a manner that surface 12 a is substantially parallel with circuitboard 14.

[0008] What is therefore needed is a technique for mounting electricalcomponents to circuit boards that overcome the foregoing and otherrelated difficulties associated with conventional electrical componentmounting techniques.

SUMMARY OF THE INVENTION

[0009] The foregoing shortcomings of the prior art are addressed by thepresent invention. In accordance with one aspect of the presentinvention, a method of mounting an electrical circuit component to acircuit board comprises the steps of providing an electrical componenthaving an electrical terminal extending therefrom, providing a circuitboard defining a bore extending from a first surface toward a secondopposite surface thereof, deforming the electrical terminal to define amounting portion having a tip portion extending away therefrom, andmounting the electrical component to the circuit board with the mountingportion of the electrical terminal juxtaposed with the first surface ofthe circuit board and with the tip extending into the bore.

[0010] In accordance with another aspect of the present invention, acircuit assembly comprises an electrical component having an electricalterminal extending therefrom, the electrical terminal defining amounting portion having a tip portion extending therefrom, and a circuitboard defining a bore extending from a first surface toward a secondopposite surface thereof. The electrical component is mounted to thecircuit board with the mounting portion of the electrical terminaljuxtaposed with the first surface of the circuit board and with the tipextending into the bore.

[0011] One object of the present invention is to provide a technique forsurface-mounting an electrical component to a circuit board.

[0012] Another object of the present invention is to provide such atechnique to simplify the construction of circuit assemblies utilizingdisplay units.

[0013] These and other objects of the present invention will become moreapparent from the following description of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will now be described, by way of example,with reference to the accompanying drawings, in which:

[0015]FIG. 1A is a perspective view of a display unit mounted to acircuit board in a known manner;

[0016]FIG. 1B is a magnified view of one of the electrical terminalsextending from the display unit of FIG. 1A illustrating variousconventional details thereof.

[0017]FIG. 2 is a cross-sectional view of the circuit assembly shown inFIG. 1 as viewed along section lines 2-2;

[0018]FIG. 3 is a cross-sectional view of an electrical circuitcomponent having a number of electrical terminals processed inaccordance with the present invention for surface mounting to a circuitboard;

[0019]FIG. 4 is a cross-sectional view of the electrical circuitcomponent of FIG. 3 shown mounted to a circuit board in accordance withthe present invention; and

[0020]FIG. 5 is a cross-sectional view of the circuit assembly shown inFIG. 4 as viewed along section lines 5-5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Referring now to FIG. 3, a cross-sectional view of an electricalcircuit component 12 is shown having a number of electrical terminalsthat are structurally modified in accordance with the present invention.As with the electrical component 12 illustrated in FIGS. 1 and 2,component 12 of FIG. 3 may include any number of electrical terminalswherein two such terminals 22 and 24 are illustrated in FIG. 3.Referring specifically to electrical terminal 22, a first section 22 athereof extends from electrical component 12 in a direction generallyparallel with top planar surface 12 a, and a second section 22 b extendsdownwardly away from section 22 a in a substantially perpendiculardirection thereto. It is to be understood, however, that section 22 bmay be configured to extend along any desired direction away fromsection 22 a. In any case, a third section 22 c extends away fromsection 22 b preferably in a direction parallel with top surface 12 a ofcomponent 12 such that a bottom surface 22 c′ of section 22 c issubstantially parallel with surface 12 a. It is to be understood thatsection 22 c may alternatively be disposed at any desired angle relativeto section 22 b such that surface 22 c′ is positioned at any desiredangle relative to surface 12 a of component 12 or to any other desiredreference surface. In any case, electrical terminal 22 includes a fourthsection 22 d extending away from section 22 c preferably in a directionperpendicular thereto. However, it is to be understood that section 22 dmay alternatively be configured to extend in any desired directionrelative to section 22 c.

[0022] In one preferred embodiment, electrical terminal 24 is configuredidentically to electrical terminal 22 such that surface 24 c′ of section24 c is coplanar with surface 22 c′ of section 22 c of electrode 22. Inthis manner, surfaces 22 c′ of electrical terminal 22 and 24 c′ ofelectrical terminal 24 provide support surfaces for supportingelectrical component 12 in the orientation shown in FIG. 3 relative to aflat planar surface such as a circuit board. Alternatively, electricalterminal 24 may be modified such that sections 24 c and 24 d arereplaced by sections 24 e and 24 f that are identical to sections 24 cand 24 d with the exception that surface 24 e′ is not coplanar withsurface 22 c′ of electrode 22. In this embodiment, electrodes 22 and 24may be mounted to two different surfaces that are not coplanar, butwherein the orientation of surface 12 a of electrical component 12 ismaintained as shown in FIG. 3.

[0023] Referring now to FIG. 4, an electrical circuit assembly is shownhaving the electrical component 12 of FIG. 3 mounted to a circuit board14 utilizing the concepts of the present invention. Circuit board 14includes a top surface 14 a and an opposite bottom surface 14 b, anddefines a number of bores or passageways 14′ and 14″ from the topsurface 14 a toward the bottom surface 14 b. In one embodiment, bores14′ and 14″ extend completely through circuit board 14 from the topsurface 14 a to the bottom surface 14 b, although the present inventioncontemplates at any one or more of the bores 14′ and 14″ mayalternatively extend from top surface 14 a toward bottom surface 14 butnot extending completely through circuit board 14. In any case, circuitboard 14 preferably includes electrically conductive pads 26 and 28disposed on the top surface 14 a thereof adjacent to bores 14′ and 14″as shown in FIG. 4. Electrically conductive pads 26 and 28 arepreferably formed from an electrically conductive film (e.g., copper).In one embodiment, the electrically conductive pads are affixed to thetop surface 14 a of circuit board 14 and patterned to form circuit padsabout each of the bores 14″ to form non-plated through holes 14″ as isknown in the art and as shown by example in FIG. 4 with reference toelectrically conductive pad 26. Alternatively, the electricallyconductive pads are affixed to the top and bottom surfaces 14 a and 14 bof circuit board 14 as well as through each of the bores 14′ to formplated through holes 14′ as is known in the art and as shown by examplein FIG. 4 with respect to electrically conductive pad 28. Those skilledin the art will recognize that plated through and non-plated throughholes are typically not provided on the same circuit board 14 as shownin FIG. 4, and that FIG. 4 is shown with each only to illustrate exampleembodiments of the present invention.

[0024] In accordance with the present invention, electrical component 12is mounted to circuit board 14 by directing electrical terminal tips orsections 22 d and 24 d into bores 14′ and 14″, respectively, from thetop surface 14 a of circuit board 14. By directing electrical terminalportions 22 d and 24 d into bores 14′ and 14″ as just described,electrical terminal surfaces 22 c′ and 24 c′ are juxtaposed with, andsupported by, electrically conductive pads 26 and 28, respectively. Animportant advantage gained with the present invention is that by placingtips 22 d and 24 d of a number of electrical terminals intocorresponding circuit board holes and applying pressure to the surface12 a of component 12, circuit board mounting surfaces 22 c′ and 24 c′ ofelectrical terminals 22 and 24 are automatically planarized with respectto the top surface 14 a of circuit board 14. This then provides flatsurfaces 22 c′ and 24 c′ suitable for attachment of electrical component12 to circuit board 14 via known wave soldering techniques.

[0025] Electrical terminals 22 and 24 are affixed to circuit board 14after assembly thereof as just described, using any known means foraffixing electrical components to circuit boards. In one embodiment, forexample, electrical terminals 22 and 24 are electrically andmechanically attached to electrically conductive pads 26 and 28,respectively, via an electrically conductive attachment media such assolder. As shown in FIGS. 4 and 5, for example, section 22 c ofelectrode 22 and/or sections 24 c and 24 d of electrode 24 is/areelectrically and mechanically attached to electrically conductive pads26 and 28 respectively via solder contact 30. It is to be understood,however, that the present invention contemplates attaching electricalterminals 22 and 24 to circuit board 14 via other known mechanismstherefore. It should also be understood that electrical component 12 mayinclude any number of electrical terminals, such as terminals 22 and 24shown in FIGS. 3-5, and that any one or more of such terminals may beattached to circuit board 14 as just described.

[0026] It should now be apparent from the foregoing description that thepresent invention provides for effectively surface-mounting anelectrical component 12, having a number of electrical terminalsextending therefrom, to a circuit board 14. In accordance with thepresent invention, the electrical terminals are structurally deformed todefine a mounting portion (22 c, 24 c) having a tip portion (22 d, 24 d)extending away from the mounting portion. The electrical component 12 ismounted to a circuit board 14 with the mounting portions (22 c, 24 c)juxtaposed in planar relationship with the top surface 14 a of circuitboard 14 and with the tip portions (22 d, 24 d) extending intocorresponding bores (14′, 14″) defined by circuit board 14. It is to beunderstood that electrical component 12 may be any electrical componenthaving one or more electrical terminals extending therefrom, althoughthe concepts of the present invention described herein are particularlyadvantageous for use with an electrical component 12 in the form of adisplay unit or device. For example, when electrical component 12 isembodied as a display unit having a viewable top surface 12 a, surfaces22 c′ and 24 c′ of electrical terminals 22 and 24, respectively, serveto support the electrical component 12 in the position illustrated inFIGS. 3 and 4, while the tip portions 22 d and 24 d extending into bores14′ and 14″ serve to maintain component 12 on circuit board 14 in placeduring subsequent component attachment processes such as, for example,wave or reflow soldering processes. The electrical terminalconfiguration of the present invention therefore provides coplanarsurfaces (22 c′, 24 c′) to facilitate mounting of an electricalcomponent 12 to a circuit board 14 with a desired orientation and/oroffset relative to circuit board 14, while maintaining properpositioning of electrical component 12 relative to circuit board 14during one or more subsequent electrical component attachment processes.

[0027] While the invention has been illustrated and described in detailin the foregoing drawings and description, the same is to be consideredas illustrative and not restrictive in character, it being understoodthat only the preferred embodiments have been shown and described andthat all changes and modifications that come within the spirit of theinvention are desired to be protected.

1. A method of mounting an electrical circuit component to a circuitboard, comprising the steps of: providing an electrical component havingan electrical terminal extending therefrom; providing a circuit boarddefining a bore extending, from a first surface toward a second oppositesurface thereof; deforming said electrical terminal to define a mountingportion having a tip portion extending away therefrom; and mounting saidelectrical component to said circuit board with said mounting portion ofsaid electrical terminal juxtaposed with said first surface of saidcircuit board and with said tip extending into said bore.
 2. The methodof claim 1 wherein said first surface of said circuit board defines anelectrically conductive pad thereon adjacent said bore; and wherein themounting step includes the steps of: positioning said electricalcomponent relative to said circuit board with said mounting portion ofsaid electrical terminal juxtaposed with said electrically conductivepad and with said tip extending into said bore; and affixing saidmounting portion of said electrical terminal to said electricallyconductive pad.
 3. The method of claim 2 wherein the affixing stepincludes mechanically and electrically attaching said mounting portionof said electrical terminal to said electrically conductive pad.
 4. Themethod of claim 2 wherein the affixing step includes soldering saidmounting portion of said electrical terminal to said electricallyconductive pad.
 5. The method of claim 1 wherein said electricalcomponent defines a viewing surface; and wherein said deforming stepincludes deforming said electrical terminal to define a mounting portionhaving a mounting surface disposed substantially parallel with saidviewing surface of said electrical component.
 6. The method of claim 5wherein said deforming step further includes deforming said electricalterminal to define said tip extending substantially perpendicularly awayfrom said mounting portion.
 7. The method of claim 1 wherein saidelectrical component includes a number of electrical terminals extendingtherefrom and said circuit board defines a corresponding number of boresextending from said first surface toward said second surface; andwherein said deforming step includes deforming said number of electricalterminals to each define a respective mounting portion having a tipportion extending away therefrom; and wherein said mounting stepincludes mounting said electrical component to said circuit board withsaid mounting portion of each of said number of electrical terminalsjuxtaposed with said circuit board and with each of said tips extendinginto separate ones of said corresponding number of bores.
 8. A circuitassembly comprising: an electrical component having an electricalterminal extending therefrom, said electrical terminal defining amounting portion having a tip portion extending therefrom; and a circuitboard defining a bore extending from a first surface toward a secondopposite surface thereof, said electrical component mounted to saidcircuit board with said mounting portion of said electrical terminaljuxtaposed with said first surface of said circuit board and with saidtip extending into said bore.
 9. The circuit assembly of claim 8 furtherincluding an electrically conductive pad disposed on said first surfaceof said circuit board; and wherein said electrical component is mountedto said circuit board with said mounting portion of said electricalterminal juxtaposed with said electrically conductive pad.
 10. Thecircuit assembly of claim 9 wherein said mounting portion of saidelectrical terminal is mechanically and electrically attached to saidelectrically conductive pad.
 11. The circuit assembly of claim 10wherein said mounting portion of said electrical terminal is soldered tosaid electrically conductive pad.
 12. The circuit assembly of claim 8wherein said bore extends completely through said circuit board fromsaid first surface to said second opposite surface.
 13. The circuitassembly of claim 8 wherein said electrical component defines a viewingsurface; and wherein said mounting portion of said electrical terminalis disposed substantially parallel with said viewing surface of saidelectrical component.
 14. The circuit assembly of claim 13 wherein saidtip portion of said electrical terminal is disposed substantiallyperpendicularly away from said mounting portion.
 15. The circuitassembly of claim 8 wherein said electrical component is a display unit.16. The circuit assembly of claim 8 wherein said electrical componentincludes a number of electrical terminals extending therefrom and saidcircuit board defines a corresponding number of bores extending fromsaid first surface toward said second surface; and wherein said numberof electrical terminals each define a respective mounting portion havinga tip portion extending away therefrom; and wherein said electricalcomponent is mounted to said circuit board with said mounting portion ofeach of said number of electrical terminals juxtaposed with said circuitboard and with each of said tips extending into separate ones of saidcorresponding number of bores.